Question Seasonic SSR-750FX fan question

[octavecode]

Hey guys...
I 'm running a Seasonic SSR-750FX + 8700k + RTX 2070 and up until now i've had the PSU fan running all the time.
I recently wanted to test out the hybrid cooling mode so i turned the fan switch off and i started stressing my system.
I measured 330-350 watts from the wall while running Prime32+Furmark for 30mins and the PSU fan didn't spin the whole time.
I eventually turned on the fan switch and the air coming out of the PSU was quite hot.
Should i RMA, is it faulty?

 

[Eugene$$]

the fan will start spinning only when it reaches certain wattage..

 

[octavecode]

I couldn't rest my mind so i got from a friend a rtx 2060 and i run a luxmark openCL stress test on both gpus (RTX 2070 + 2060) plus prime95 on the cpu. 470watts from the wall and i had to wait 5 mins for the PSU fan to start spinning automatically.
I guess the psu works just fine. Cheers.